如何在 PostgreSQL 中找到一个值保持相同状态的最大时间差？

Question

我正在为一个大学项目工作，我想到了这个：

我有一个 table 这样的：

我想获得执行器处于某个状态的最长持续时间。例如，cool0 是 18 分钟。

结果 table 应如下所示：

NAME         COOL0   
State        False
Duration     18

Answer 1

这是一个缺口和孤岛问题。你的数据有点难以理解，但我认为：

select actuator, state, min(actuator_time), max(actuator_time)
from (select t.*,
             row_number() over (partition by actuator order by actuator_time) as seqnum,
             row_number() over (partition by actuator, state order by actuator_time) as seqnum_s
      from t
     ) t
group by actuator, (seqnum- seqnum_s)

对于每个执行器的最大值，使用 distinct on:

select distinct on (actuator) actuator, state, min(actuator_time), max(actuator_time)
from (select t.*,
             row_number() over (partition by actuator order by actuator_time) as seqnum,
             row_number() over (partition by actuator, state order by actuator_time) as seqnum_s
      from t
     ) t
group by actuator, (seqnum- seqnum_s)
order by actuator, max(actuator_time) - min(actuator_time) desc;

如何在 PostgreSQL 中找到一个值保持相同状态的最大时间差？

How to find the max time difference in PostgreSQL that a value stayed on the same state?

sql

postgresql

gaps-and-islands